It's going to be different for everyone, you'll have to find what works for you, but I drink Diet Pepsi and the WalMart brand of the flavored waters. I drink several bottles of those waters every day. So Good!!

I squeeze fresh lemon into my bottled water, because lemon alkalizes it and because straight water tastes metallic and slightly bitter when I am in ketosis. Sometimes I add a little ACV instead of lemon.

I make plain iced tea, like the newmans organic, and add lemon slices, a pack of the lon flavor sticks with stevia, plus a couple packs of trivia or Splenda. The hug lasts me a couple of days and is close to the southern sweet tea which I love.
We have great crushed ice at work and I have a diet coke over the ice, so 3 days a week I allow a diet drink, which I think are not so good for me. Also if you need bubbles, there is Zevia made with Stevia.

I have major issues with plain water. Not sure why I don't care for it so much. I drink unsweetened iced tea all the time. It's not for everyone, but if you like your coffee black, you might like the "bitter" quality of unsweetened tea. You can drink unsweetened fruit infused teas too. I drink this all the time, even the times I haven't been watching my carbs. I prefer the flavor of unsweetened.

When I was younger, drinking plain water would give me heartburn. I have no idea why, but if it were tea or flavored, it wouldn't happen. unsweetened green tea is a treat. If you can find barley tea bags that's very nice and refreshing too, very clean tasting and no caffienne.

I found out recently that if I add a touch of magnesium, baking soda and calcium powder to my half liter bottle and fill it with water, then it's much easier to drink than even my Brita filtered water. There is no taste, just a smoother mouthfeel that doesn't feel sharp going down like plain water often feels to me. I can drink several gulps at a time of this electrolyte water vs just a few sips at a time of plain filtered water.

I use the kool aid, crystal lite, or mio drops (whichever is on sale). I don't make it very strong, just enough to give some flavor.

Later, if you want to have an alcohol drink, these drops are good to add to vodka/soda! I've done this a few times and have not noticed a difference in my weight loss. Of course, I wouldn't do this every day, but once every couple of weeks or so.

mio with seltzer. The orange tangerine is really good when you add a drop of vanilla extract or vanilla davinci. The grape dasani water enhancer tastes good with water or seltzer at the beach. I don't mix them very strong-- just a hint of flavor, not nearly as strong tasting as an orange or grape soda.

I also like celestial seasonings fruit teas---the raspberry, mixed berry, and cherry are my favorites. I make weak tea to sip iced.